What are the minimum parallax requirements for successful motion tracking?
The tracking points are better to be chosen from different dimensions as they are in real world, in order to cover more obvious parallax difference between frames.

For example, it's certainly not recommended to pick them all from a single plane/ground or a single wall. However, if some are from the ground and others are from a wall, it would be the nicer choice for sure.

I'm not going to propose any AD here, but I learned this thing from the official training DVD - Track, Match, Blend!